People often ask how well do solar panels work in winter when the temperatures are below freezing point and days are short with less sun? One might think that solar panels would generate the most electricity in a hot and sunny climate. But a closer look at how solar panels work quickly dispels this notion.
There is a common misunderstanding that solar panels do not work well during the winter season. While it is true that solar panels generate the most energy when exposed to direct sunlight at comfortable temperature around 77 degrees Fahrenheit, the temperature dropping close to freezing does not have a significant impact on their performance. Let’s see why.
Solar panel winter efficiency: Cold temperature and panel performance
Solar panels are also commonly referred to as photovoltaic (PV) panels. One solar panel contains many photovoltaic cells, usually 60 or 72 cells that convert energy from sunlight into electrical energy we can use.
Solar cells are made of a semiconducting material like crystalline silicon, containing a positive layer and a negative layer to create an electric field. When sunlight hits the cells, it causes a flow of electrons from the negatively charged layer to the positively charged layer. This electron movement generates an electrical current that can be used to power homes.
It is the sunlight not the heat that the solar cell uses. In fact, heating the material through which the electric charge flows increases resistance and slows down the flow of electrons.
If conductors are attached to the positive and negative sides of a solar cell, it forms an electrical circuit. The electrons flow through this circuit, creating electricity. The faster the electrons flow, the higher the voltage output.
It may be surprising, but cold weather can help solar panels produce more energy. Solar panels are like other electronic devices such as computers, radios, and household appliances, they tend to work rather more efficiently in colder weather than in hot temperatures.
How well do solar panels work in winter?
Colder temperatures could do well for the overall system performance compared to hotter temperatures, when excessive heat leads to overheating and a decrease in the efficiency of energy conversion.
When solar panels get too hot, the voltage at their output drops, which reduces the overall power output of solar panels on hot days. This is because the higher temperature increases the resistance of the electrical circuit, which causes energy losses. The amount of energy lost due to excessive heat varies depending on the design of the solar panel and the specific conditions.
Conversely, resistance decreases with decreasing temperatures. For example, in polycrystalline PV panels, if the temperature decreases by one degree Celsius, the voltage increases by 0.12 volts.
In fact, solar panels often work more efficiently in colder temperatures compared to hotter temperatures, as excessive heat can lead to a decrease in the panels' efficiency.
The amount of sunlight that solar panels receive during the winter months is often sufficient to generate a decent amount of energy. Yes, the days are shorter and there is less sun in general, but the sun rays may hit during peak hours the solar panels more directly because of the angle of the sun in the sky, leading to a higher energy output from those few hours of sun in a day. Additionally, solar panels still work even in cloudy conditions.
Although cold temperature on its own does not have a negative impact on solar panel performance, other factors such as snowfall could influence the final energy production.
What happens when there is snow on solar panels?
While snow on solar panels is typically not a major issue, it’s important to understand how it will affect your solar system.
Snow and ice buildup on the panels prevents sunlight from reaching the solar cells. The accumulation of snow creates a barrier that prevents sunlight from penetrating the surface of the solar panel, which reduces the amount of energy that is generated.
But this problem has an easy fix. Because a solar panel begins to heat up once sunlight hits it, even just removing a small amount of snow from a panel can kickstart the heating process and hasten snow melting from the rest of the panel.
Solar panels have smooth surfaces. They become slippery when wet. And they are typically installed facing south or southwest, so when the sun comes out, snow should quickly melt and slide off on its own.
The positive side of snow on the ground is that the reflection of sunlight on snow means more available light for the solar panel to convert into electricity.
So, while intuitively one might think solar panels work better in hot climates, the fact is that they can produce more power on a sunny winter day in New Jersey than a blazing hot summer day in Arizona.
Remember: snowfall on the ground can create more available reflective light and it is the light from the sun that is converted into electricity, not heat.
The problems caused by snow on solar panels are usually nothing you should worry about when it comes to taking care of your solar system.
All solar panels are built to withstand a specific amount of weight, and snow is usually not heavy enough to cause any problems. Manufacturers conduct pressure tests on solar panels to ensure their durability and quality. If you live in an area with tough winter, solar panels with higher pressure ratings should better handle heavy snow weighting them down once a while.
Do solar panels produce less in winter?
Solar panels produce on average slightly less electricity in winter compared to other seasons because of the shorter days with less sun. However, modern solar panels are becoming more efficient, which helps to offset some of the losses due to less sunlight anyway.
The reduction in energy output is not as significant as many people believe. A well-designed solar system for your house should produce sufficient amount of energy throughout the season to offset the losses for a couple of weeks with unsuitable conditions.
Solar panel output winter vs. summer
Solar panel output naturally varies between winter and summer due to factors like the length of the day, the angle of the sun and snow cover.
Generally, solar power generation is lower during the winter months, with energy output dropping by 40 to 60 percent during December and January when compared to June and July.
The average output of solar panels will differ based on your location. Depending on where you live, you may have dry, sunny winters and your solar panels may produce more than in rainy summers with blazing heat. Other locations that get lots of snow or foggy overcast days may experience a bigger drop in solar production.
One major difference between winter and summer is the length of the day. In winter, days are shorter. The hours of sunlight available to generate electricity are limited during December and January.
The angle of the sun is also an important factor to consider. The sun is lower in the sky, which can make it more difficult for solar panels to absorb the light. It’s important to ensure that your solar panels are angled correctly to maximize sunlight absorption during the winter months.
When considering the installation of a solar system, it may be better to choose panels with higher efficiency ratings if you live in an area with unfavorable winters. Make sure you work with a qualified installer who can ensure that your system is designed and installed to maximize performance year-round.
But do not worry, solar panels are a sturdy piece of equipment with simple design and functionality. They are designed to withstand harsh weather conditions, including winter storms. They are built to withstand wind, snow, ice, and hail and are tested to ensure their durability. Your trust in this renewable form of energy will pay back in the long term.